In both gasoline engines and diesel engines, which typically operate in a 4-stroke Otto or Diesel cycle, a large fraction of the fuel energy is not converted to work, but instead leaves the system as thermal energy in the form of hot combustion gases and hot engine coolant. Attempts have been made to operate engines in a 6-stroke engine cycle in which water is injected in an attempt to recover energy from the hot combustion gases. However, improvement remains desirable.
The present disclosure provides engines which operate on an improved six-stroke cycle having water injection directly into the combustion chamber which offer improved operating efficiency of the engines.